The present invention relates to a serial scanner apparatus for reading an original document by reciprocally scanning a carriage having reading means, an error correction method for the serial scanner apparatus, and a storage medium.
According to a conventional scanner apparatus for reading an original document by reciprocally scanning a carriage having reading means, because of a play (mechanical tolerance) existing in a driving system of the carriage which causes the reading means to scan, a bi-directional deviation is generated when an image is obtained by reading the image bi-directionally. Since the bi-directional deviation varies due to unevenness in a manufacturing stage or varies depending on the apparatus, the deviation has conventionally been avoided by reading an image in one direction only.
However, although such technique enables avoiding bi-directional deviation, it only allows one-directional image reading, wasting time for a carriage return. Thus, image reading is time consuming.
In view of the above, another attempt has been made to read an image bi-directionally. More specifically, bi-directional deviation was measured for as many test machines as possible, and a statistical central value was obtained from distribution of the measured values. Then, by adjusting the read-start timing, influences of the varied deviation which depends upon the apparatus was minimized. However, because the correction value is not optimized for each apparatus, satisfactory effect could not be achieved.
In addition, switch means such as a DIP switch or the like may be used in order to make the read-start timing variable in plural stages. According to this technique, an actually read image is displayed on a display screen and deviation compensation can be adjusted for each apparatus while viewing the displayed image. However such technique is problematic because adjustment is time consuming, the technique lacks mass-producibility, and re-adjustment is required since the play in the carriage system varies over time.
The present invention is made in consideration of the above situation, and has as its object to provide a serial scanner apparatus, a correction method thereof, and a storage medium for performing highly precise bi-directional image reading and greatly improving the image reading speed.
In order to solve the aforementioned problems and achieve the object, the serial scanner apparatus according to the present invention is characterized by the following configuration.
More specifically, a serial scanner apparatus comprises: reading means, mounted on a carriage, for bi-directionally reading image data of a bi-directional error correction image by reciprocally moving the carriage in a predetermined area including the image; correction value calculation means for calculating an error correction value by comparing image data obtained during forward reading of said reading means with image data obtained during backward reading of said reading means; and correction means for correcting a bi-directional error by using the calculated error correction value.
Furthermore, a bi-directional error correction method of a serial scanner apparatus according to the present invention is characterized as follows.
More specifically, a bi-directional error correction method of a serial scanner apparatus comprises the steps of: bi-directionally reading, with reading means, image data of a bi-directional error correction image on a reading material by mounting the reading means on a carriage and reciprocally moving the carriage in a predetermined area including the reading material; calculating an error correction value by comparing image data obtained during forward reading with image data obtained during backward reading; and correcting a bi-directional error by using the calculated error correction value.
Furthermore, a storage medium according to the present invention is characterized by the following configuration.
More specifically, a storage medium storing a program in the form readable by a computer of a serial scanner apparatus, said program comprises the steps of: bi-directionally reading image data of a bi-directional error correction image by reading means mounted on a carriage by reciprocally moving the carriage, having the reading means, in a predetermined area including a reading material having the bi-directional error correction image; calculating an error correction value by comparing image data obtained during forward reading of the reading means with image data obtained during backward reading of the reading means; and correcting a bi-directional error by using the calculated error correction value.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.